1. Field of the Invention
The invention relates to a filter apparatus and more particularly to a self-cleaning, back-flushable filter for removing particulate material from a pump intake.
2. Description of the Related Art
Submersible pumps are often lowered into fluid supplies such as those found in well casings or ponds in order to remove the fluid that is found there. Often, the fluid contains sand and other abrasive particles that are a constant cause of inefficiency in and potential failure of the pumping systems. For example, sand can cause severe damage to the pump and valves in the pumping system.
Many types of filters have been designed for use with submersible pumps. Such filters have typically included a filter element designed to screen particulate material from the pump intake. However, the particulate material often becomes entrapped in the filter element. The quantity of particulate material collected on the filter element is directly proportional to the to the pressure drop that occurs across the filter element. Since an excessive pressure drop across the filter element can significantly reduce fluid flow, the filter element must be periodically changed or cleaned. Often, this is done by removing the submersible pump from the fluid and removing the filter element. This can be a timely and inconvenient process. Pumps with intricate backwashing systems have been designed, but these are often expensive and cannot be used to retrofit existing systems. As a result, many pumps are generally operated without any filter and therefore experience early pump failure and extensive and costly down time.
There exists, therefore, a continuing need for further improvements in fluid filter devices having a self-cleaning filter element. There further exists the need to have a relatively simple and reliable manner of backwashing filter elements used with an existing pump.
To clean water down to hyperfiltration, nanofiltration and ultrafiltration sizes, cross flow filtration with a pressure gradient has been employed. While this has proven successful, it is also expensive due to the disposal and/or treatment of resulting concentrate of contaminants. New methods are needed to eliminate or drastically reduce the concentrate in order to provide low cost filtration of fluids, such as drinking water.